Selection of Some Promising Genotypes from Three F2 Segregating Populations in Bread Wheat under Drought Stress Conditions Using Cluster Analysis

Abstract

Selection in early generations involving evaluation of F2 genotypes is an effective procedure in breeding programs, because the inferior F2 genotypes are discarded and the more promising lines are selected and continue to the advanced generations. An experiment was conducted to study the variability and relationship between F2 genotypes derived from three different crosses. Gemiza (an Egyptian variety) was crossed with each of three exotic lines, (Line1, Line2 and Line3) that were imported from ICARDA. From each cross,50 F2 genotypes were chosen randomly. These genotypes and the four parents were evaluated for seven agronomic traits under drought conditions (60% field capacity) in Elmaghara research station in north Sinai, Sinai, Egypt, in 2011. Significant genotypic differences were observed between the genotypes in each cross for all measured traits indicating considerable amount of genetic variation generated in each segregating population. The clustering pattern in F2 progenies varied according to parental combination, and there was appreciable differences and clear separation in variable groups. The three F2 populations showed four, three and four groups of clusters at dissimilarity low than 15. Each dendrogram presented a cluster consisted of some genotypes with higher grain yield and others with desirable combinations of traits. The highest clusters under drought were fourth, third and third in the three populations respectively. The genotypes in these clusters surpassed the two parents and the other genotypes under drought conditions (60% field capacity). Therefore these genotypes should be selected to the advanced generations in a breeding